Typically, a rotor assembly for an aircraft engine has a rotor disk and one or more arrays of rotor blades. The rotor blades extend outwardly into a working medium flow path such as air. The rotor blades engage the outer periphery or rim region of the rotor disk. The rim region of the rotor disk is defined generally by axially oriented slots that receive the roots of the rotor blades.
The working medium gases exert a tangential force and an axial force on the blades as the gases flow through the rotor assembly. The axial force on the rotor blades urges the rotor blade bases axially forward relative to the movement of aircraft carrying the engine and out of the axially oriented slots. Lock means are provided to lock the rotor blades against this forward axial movement. These locks add to the rotational mass of the rotor assembly and must be carried by the rotor disk.
If a rotor blade suffers a foreign object strike, however, the rotor blade tends to rotate about the points where the foreign object strikes sending the rotor blade's root forward relative to the movement of aircraft within the rotor disk. For this reason, to protect the integrity of the rotor and the rest of the engine, lock means are also provided to lock the rotor blades from moving axially forward.